Ios – How to avoid Touches cancelled event

cocoa-touchiostouchescancelleduitouch

I have two views one beneath the another. I'm rotating the below view by touch sensing of top view. while trying to make a swipe, touches canceled event is called before touches ended event. While moving the finger touches began and touches moved events are called , and then touches ended event is called at the last(mostly). But sometimes while trying to move slowly,touches canceled event is called stopping the touch events to occur. So i couldn't rotate view in slow speed. What may be the problem? how to avoid touches canceled event?

Note: I'm drawing some graphs in views using core-plot lib.

Best Answer

If you are using any UIGestureRecognizers they automatically cancel touches to other views when they recognize their gesture. You can turn this behavior off with the cancelsTouchesInView property of the recognizer.

Related Solutions

Ios – How to disable the UITableView selection

All you have to do is set the selection style on the UITableViewCell instance using either:

Objective-C:

cell.selectionStyle = UITableViewCellSelectionStyleNone;

[cell setSelectionStyle:UITableViewCellSelectionStyleNone];

Swift 2:

cell.selectionStyle = UITableViewCellSelectionStyle.None

Swift 3 and 4.x:

cell.selectionStyle = .none

Further, make sure you either don't implement -tableView:didSelectRowAtIndexPath: in your table view delegate or explicitly exclude the cells you want to have no action if you do implement it.

More info here and here

Ios – How to sort an NSMutableArray with custom objects in it

Compare method

Either you implement a compare-method for your object:

- (NSComparisonResult)compare:(Person *)otherObject {
    return [self.birthDate compare:otherObject.birthDate];
}

NSArray *sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(compare:)];

NSSortDescriptor (better)

or usually even better:

NSSortDescriptor *sortDescriptor;
sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"birthDate"
                                           ascending:YES];
NSArray *sortedArray = [drinkDetails sortedArrayUsingDescriptors:@[sortDescriptor]];

You can easily sort by multiple keys by adding more than one to the array. Using custom comparator-methods is possible as well. Have a look at the documentation.

Blocks (shiny!)

There's also the possibility of sorting with a block since Mac OS X 10.6 and iOS 4:

NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingComparator:^NSComparisonResult(Person *a, Person *b) {
    return [a.birthDate compare:b.birthDate];
}];

Performance

The -compare: and block-based methods will be quite a bit faster, in general, than using NSSortDescriptor as the latter relies on KVC. The primary advantage of the NSSortDescriptor method is that it provides a way to define your sort order using data, rather than code, which makes it easy to e.g. set things up so users can sort an NSTableView by clicking on the header row.